Use Of Muscle Saturation Oxygen As A New Marker Of Fatigue In Female Soccer Players

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According to UEFA, a paucity of relevant studies has led to a significant increased interest in women's soccer research. Additionally, early detection of muscle fatigue could have profound impact on injury prevention and recovery in many sports including soccer. Measurement of muscle oxygen saturation (SmO2%) with non-invasive near infrared spectroscopy (NIRS) technology has been investigated as a possible indicator of fatigue, however no clear protocol exists regarding interpretation of NIRS data or its application for training assessment or fatigue detection. PURPOSE: To evaluate SmO2% kinetics and relate it to markers of fatigue induced by an official match. METHODS: 12 female soccer players (age 19 ± 3 years, weight 59.1 ± 5.7 kg, height 1.61 ± 0.05 m, Fat 18.5 ± 3.5%). They were evaluated pre-match (PRE) and 24 hours after an official match (POST). Blood plasma parameters were measured including Blood Urea Nitrogen (BUN), Glutamate-Pyruvate Transaminase (GOT) Lactate Dehydrogenase (LDH), Creatine phosphokinase (CPK), and total hemoglobin (THb). Additional outcomes were assessed including rate of perceived exertion (CR-10 Borg scale), Visual Analog Scale (VAS-pain 1-10), and "Repeated Ability Sprint Test" (RAST) using a portable "Muscle Oxygen Monitor" (MOXY) placed in the gastrocnemius muscle of the dominant leg to measure SmO2%. Deoxygenation rate (De-Oxy) and Reoxygenation Rate (Re-Oxy) were calculated. For statistical analysis, T-test, Pearson correlation and mechanical inferential statistics were applied to measure the magnitudes of change. RESULTS: Average SmO2% during test RAST increased after match ((23 ± 8 vs. 29 ± 8 p <0.05); Δ% = 19.1%), as well minimum SmO2% values (12 ± 8 vs. 21 ± 8 p <0.05) and maximum values (31 ± 8 vs. 36 ± 8 p <0.05). Other fatigue markers increased too after match, LDH (282 ± 45 vs. 341 ± 79 IU/L p<0.05) and VSA pain (3.2 ± 1.7 vs. 5.1 ± 1.7 p <0.01). It was also found that a higher Re-Oxy corelated with increases in LDH (r = 0.88 p <0.01), VSA pain (r = 0.61 p <0.05) and BUN (r = 0.84 p <0.01). Taken together, the decrease in SmO2% was considered as the best performance in the RAST test (r = -0.79 p<0.01). CONCLUSIONS: MOXY monitor can be used as a novel, non-invasive method to identify post-match fatigue in female soccer players through measurement of SmO2% kinetics and the rate of reoxygenation.